Recently, high-performance microprocessors have been developed, and a computer unit (ECU (Electronic Control Unit)) including many microprocessors has been incorporated into a vehicle such as an automobile. The ECUs are for pursuing driving performance, safety, comfort, resource saving, energy saving and the like, and they are incorporated into a vehicle for controlling its power train system, body system, safety system, information system and the like.
There are ECUs respectively controlling an engine, a brake, a steering device, a suspension, and a transmission as a vehicle motion system (an ECU may integrally control part of or all of them), ECUs respectively controlling a power door, a power seat, an air conditioner, and an illumination as a body system, ECUs respectively controlling an air bag and collision sensor as a safety system, and ECUs respectively controlling a car navigation device and car audio device as an information system. An in-vehicle network has been employed for reducing the wire harnesses involved with an increase in the number of ECUs.
In a vehicle control system constituted by ECUs connected to such an in-vehicle network, a power train system ECU corresponding to a “running” operation that is the basic operation of the vehicle, a brake system ECU corresponding to a “stop” operation, and a steering system ECU corresponding to a “turning” operation are provided operable in a manner independent of each other. In addition to these basic control units, a processing unit is applied such that the driving operation corresponding to the vehicle environment, driving support for the driver, and vehicle dynamic motion control can be conducted automatically in a parallel manner. These processing unit and basic control units may be configured with an upper-lower level relationship, or without constituting an upper-lower level hierarchy.
In such a vehicle control system, a failure occurring in one of many ECUs must be accurately sensed, or various problems may be invited. Accordingly, a failure detection program for detecting a failure in each part of a vehicle has been incorporated into a vehicle in order to improve the reliability. Specifically, it is for automatically checking the operation status of a computer portion, sensors or the like by an appropriate cycle, and storing diagcode or the like upon failure. Thus, a maintenance man reads the diagcode or the like stored in the electronic control unit by connecting a dedicated tool, and specifies the location of the failure.
Japanese Patent Laying-Open No. 2003-019931 (Document 1) discloses a failure diagnosis system that permits appropriate determination of a problem caused by a cooperative operation of a plurality of electronic control units connected through an in-vehicle network, and an immediate specification of the location of a failure. The failure diagnosis system includes a plurality of electronic control units connected through an in-vehicle network and having a failure detection program for detecting a failure of a vehicle in controlling a control target, and a vehicle management device communicating with the electronic control units through the in-vehicle network to perform a vehicle failure management. The vehicle management device includes: problem determination means for determining an occurrence of a problem based on data of an electronic control unit passed through the in-vehicle network; program obtain means for obtaining a test diagnosis program prepared in advance corresponding to the problem when the occurrence of the problem is determined by the problem determination means; failure location specification means for executing the test diagnosis program obtained by the program obtain means, thereby causing a corresponding electronic control unit to perform an addressing process, and thereby specifying the failure location based on information transmitted from the electronic control unit; and information output means for outputting failure information related to the failure based on a process result by the failure location specification means.
According to the failure diagnosis system, since an occurrence of a problem is determined based on data of an electronic control unit passed through a network, an occurrence of a problem related to the cooperative operation among the electronic control units can also be determined. Additionally, since a test diagnosis program prepared in advance is used and the failure location is specified by causing the applicable electronic control unit to transmit an internal variable in specific control, for example, it is highly possible that the failure location is specified immediately.
On the other hand, according to the disclosure of Document 1, the vehicle manager ECU monitors data of respective ECUs on the in-vehicle network and determines a failure. In other words, it determines a problem related to the cooperative control among the ECUs from failure detection result data by a failure detection program executed at each ECU, and data exchanged among the ECUs through the vehicle manager ECU. The vehicle manager ECU obtains a test diagnosis program corresponding to the problem from a client server, executes the obtained test diagnosis program thereby causes the corresponding ECU to perform an addressing process, and specifies the failure location by causing the corresponding ECU to transmit an internal variable in specific control or the like, for example. Therefore, the vehicle manager ECU must be implemented with a function as an original vehicle management device in addition to a function of monitoring numerous ECUs. Thus, the calculation load of the vehicle manager ECU increases, and the ECU requires a computer that is highly reliable, capable of high-speed calculation and with high performance. Such an ECU is expensive, and therefore increases the costs. Furthermore, centralizing the functions to the vehicle manager ECU, when there is a failure (including a failure due to high load, a failure due to a hardware trouble and the like) in the vehicle manager ECU, functions of the power train system ECU corresponding to a “running” operation that is the basic operation of the vehicle, the brake system ECU corresponding to a “stop” operation, and the steering system ECU corresponding to a “turning” operation, which are managed by the vehicle manager ECU, may be weakened.